Spark-plug for internal-combustion engines



y W. EL TAFT. s P'Agx PLUG-noa INTERNAL comeuslon ENGINES. APPucUloN ruin um. s. |911.

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Patented Jan.\.20,1920.

UNITED STATES PATENT oFFroE.

WALTER EVERETT TAFT, OF PROVIDENCE, IODE ISLAND, ASSIGNOR T0 THE ASSOCIATE COMPANY, OF BOSTON, MASSACHUSETTS, A COlEl/POIXJBJIIONv OF MASSACHUSETTS.

SPARK-PLUG FOR INTERNAL-COMBUSTION ENGINES.

Specification of Letters Patent.

Patented Jan. 20, 1920.

Application led March 6, 1917. Serial No. 152,863.

To all whom t may concern:

Be it known that I, WALTER EVERETT TArT, a citizen of the United States, 'residing at Providence, in the county of Providence and State of Rhode Island, have invented cert-ain new and useful Im rovements in Spark-Plugs for Internalo mbustion Engines, of which the following is a specification.

This invention relates to improvements in spark-plugs for use in internal combustion engines and the object of my improvement is to produce a spark-plug in which the lia- `of the inside washer shown in Fig. 3.

p Fig. 5 is a sectional view, corresponding to Fig. 3 of a modified arrangen'ient oi' the washers used for the outer electrode.

Fig. 6 is a plan view of the plug with the conducting wire at oneside of the center of.. the hole in the electrode.

A4Fig. 7 is another modification showing a diierent arrangement of the washers for the cater electrode.

My improved spark-plug comprises a body 1 inclosing a chamber 2, is provided withfa suitable insulating structure 3, and has for the electrodes the straight, axially positioned wire 4 for the inner electrode and for the outer, coperating electrode a Washer-like structure composed as shown oia pair of Washers placed face toiace, respectively a top or outer Washer 5 and an inner washer 6.

The washers 5 and 6 are concentric with the wire 4, the said wire passing entirely through the holes in the said washers, the diameter of the wall of the said holes being somewhat larger than the diameter of the wire so that the said wall is in spaced relation to the Wire.

The walls of the holes 7 and 8 in the individual washers 5 and 6 are of counter-` sunk or beveled form, and the washers are placed together with the larger ends ol the holes adjacent or opposed one to the other, the two washers as a unit being rigidly held in position, which is at the sparking end of the spark-plug structure. Accordingly the border wall of .the opening that is op posed to the Wire 4 as a Whole is in the .form oi a pair of inwardly projecting` annular ribs having a V-shaped form of crosssecton and formed by the edge portions atthe smaller ends of the holes in the individual washers, and these ribs are separated by arecess of appreciable depth and width, the depth being due to the inclination of the bevel and the width at the tips corresponding to the combined thickness of the two washers.

As shown, washers 5 and 6 are alike.

In some cases I may have the hole in'the `individual washers of slightly diii'eent diameter, the one with the smaller diameter serving as the vactive electrode or electrode proper. A

In Fig. 5 an additional washer 6 is shown below to the Washers 5 and 6, being otherwise arranged as described above.

In Fig. 6 'the wire electrode 4 is shown to one side of the center of the outer electrode 5.

In Fig. 7 the Washers 5 and 6 are placed with the beveled side walls of the holes directed in the saine direction, the large end of the hole in one being opposed to the small end of the hole in the other.

Other arrangements of the washers may be also used, it being im ortant to avoid any arrangement that woul interfere with providinf a sharp edge for the active portion.

Tl said sharp edge or rib serves most eiectively for sparking with high potential and at the same time tends to remain clean because-of the absence of a seat to which ioul particles can adhere.

The provision of a plurality of ribs with the intervening recess providesa restricted passage of.nonuniform cross-section, that has a choking effect on the ases bearing foul matter and foreign partie es so that the flow of such gases in and out of the chamber 2 is retarded or checked, and the tendency to foul and become short circuited is reduced to a minimum Such ilow of gases is a surging effect due to the impulses of the explosive mixture in the cylinder and has a tendency if unre- Strieted to deposit short-eireuiting material on the electrodes.

The gap between the inner, insulated electrode 4, of wire, and the Outer, grounded electrode formed bythe washers 5 and 6 is relatively small, so that it would be difieult and essentially iinp noticable to provide the peculiar form for the wall of the opening in the grounded electrode. suoli as described, in a unitary structure, whereas by the expedient ol using a plurality of separate Washers, eaeh individually provided with a hole haviufg a simple beveled wall.` and placed together to make a compositel stmmtnre, the desired condition for proper operation is conveniently obtained.

Thus a non-cylindrical foi-1n of cross-section is provided for the wall oi: the said opening, 'which nray be designated as wavy, or undulating, or corrugated, and the same .is built up of elements having the border wall l'or the opening of simple form, being divergent relatively to the axis continuously iu one direction.

l claim as my invention:-

l. In a spark plug, comprising a pair of electrodes 'for eoperating one With the other, one of the said el eotrodes being in the forni ol a straight wire, and axially positioned in the spark plug structure, the other o." the said electrodes consisting of a Washerlike structure -having an opening ro which the said Wire extends, 'the Walls of the said opening opposed to the said Wire in spaced relation to the said Wire, sr walls being in the form of a plurality oit iu- Wardly projecting annular ribs having le V-shaped cross-section, the adjacent ribs being separated by a ree-ess oit appreeial' Width and depth, and the said Waslie""l structure being composed of a plural Washers eaeh of which has a hole ivitb. led Side walls.

2. A spa1l;plug comprising an insulated electrode of Wire and a grounded eleetrof ,having an opening eoneentrie with the Wire, the said opening being of relati small diameter so that the Wall of the said opening' is separated from 'the said Wire bf: a relatively small gap, `th(` said wall of lil opening being ol non-cylindrieal forni fr moss-section, comprising sharp, iange-lil' portions at the ends, connected by a tivelyY deep valley orjreeess, and 'the a grounded electrode being built up of of Washers, each of the said vviashers lia a beveled border Wall for the opening, 5 the two Washers being,- placed together the faces corresponding to the of the Washer openings opposed ann abutment.

WALTER EVERETT TFT,

Wi tnesses r C. J. ROACH,

`ino. A. STARK. 

